Rotation mechanism with sliding joint

ABSTRACT

Rotation mechanisms for rotating a payload in two, first and second degrees of freedom (DOF), comprising a static base, a first rotation arm coupled mechanically to the static base through a first rotation joint and used for rotating the payload relative to the static base around a first rotation axis that passes through the first rotation joint, a second rotation arm coupled mechanically to the static base through a second rotation joint and used for rotating the payload relative to the static base around a second rotation axis that passes through the second rotation joint, and a follower member rigidly coupled to the payload and arranged to keep a constant distance from the second rotation arm, wherein the rotation of the first arm rotates the payload around the first DOF and the rotation of the second arm rotate the payload around the second DOF.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 371 application from international patentapplication PCT/IB2019/061360 filed on Dec. 25, 2019, which claimspriority from US Provisional Patent Applications No. 62/789,150 filed onJan. 7, 2019 and No. 62/809,897 filed on Feb. 25, 2019, both of whichare expressly incorporated herein by reference in their entirety.

FIELD

Embodiments disclosed herein relate in general to rotation mechanism andin particular to rotation mechanisms for various elements in smalldigital cameras included in electronic devices.

BACKGROUND

Cameras for surveillance, automotive, etc. include mechanisms thatenable advanced optical function such as optical image stabilization(OIS) and/or scanning the camera field of view (FOV). Such mechanismsmay actuate (e.g. displace, shift or rotate) an optical element (e.g.lens, image sensor, prism, mirror or even an entire camera) to createthe desired optical function. Rotation mechanisms for rotating a payload(e.g. an optical element as above) in two degrees of freedom (DOF) areknown. In known mechanisms in which one DOF is an internally rotatingDOF and the other DOF is an external DOF, there is normally a problem inthat the internally rotating DOF has its rotation axis rotated by theexternal DOF (Gimbal design). Known rotation mechanisms that solve theGimbal problem use two fixed (not rotating) motors with more than threebearings or two rotating motors with two bearings.

SUMMARY

Aspects of embodiments disclosed herein relate to rotation mechanismsfor rotating a payload in two DOFs. We propose a method of having tworotation axes around two rotation points.

In various exemplary embodiments there are provided rotation mechanismsfor rotating a payload in two, first and second DOFs, comprising astatic base, a first rotation arm coupled mechanically to the staticbase through a first rotation joint and used for rotating the payloadrelative to the static base around a first rotation axis that passesthrough the first rotation joint, a second rotation arm coupledmechanically to the static base through a second rotation joint and usedfor rotating the payload relative to the static base around a secondrotation axis that passes through the second rotation joint, and afollower member rigidly coupled to the payload and arranged to keep aconstant distance from the second rotation arm, wherein the rotation ofthe first arm rotates the payload around the first DOF and the rotationof the second arm rotate the payload around the second DOF.

In some embodiments, the follower member is a magnetic member separatedfrom the second rotation arm by a constant air-gap.

In some embodiments, the payload is coupled mechanically to the firstrotation arm through an inner rotation joint.

In some embodiments, a rotation mechanism further comprises a firstmotor for rotating the payload relative to the static base around thefirst rotation axis and a second motor for rotating the payload relativeto the static base around the second rotation axis, wherein the firstand second motors are rigidly attached to the static base

In some embodiments, the second rotation arm is a ring section centeredaround the first rotation axis.

In some embodiments, the rotation mechanism further comprises at leastone sensing mechanism for determining a position of the payload.

In some embodiments, a sensing mechanism comprises at least one pair ofa magnet and a Hall sensor.

In some embodiments, a sensing mechanism is operable to determine aposition of the payload relative to the static base in the first andsecond DOFs.

In some embodiments, a pair of a magnet and a Hall sensor comprises afirst pair of a magnet and a Hall sensor that allows determination of arotation of the payload around the first DOF, and a second pair of amagnet and a Hall sensor that allows determination of a rotation of thepayload around the second DOF.

In some embodiments, determinations of the position of the payloadrelative to the static base in the two DOFs are decoupled from eachother.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects, embodiments and features disclosed herein will become apparentfrom the following detailed description when considered in conjunctionwith the accompanying drawings, in which:

FIG. 1A shows schematically in a perspective view an embodiment of arotation mechanism for rotating a payload in two DOFs disclosed herein,at zero position;

FIG. 1B shows the mechanism of FIG. 1A coupled with exemplary first andsecond motors;

FIG. 1C shows in side view the mechanism of FIG. 1A at at zero(non-rotated) position;

FIG. 1D shows in side view the mechanism of FIG. 1A at a rotatedposition around the first rotation axis;

FIG. 1E shows the rotation of a second rotation arm in the mechanism ofFIG. 1A around a second rotation axis;

FIG. 2A shows schematically in a perspective view another embodiment ofa rotation mechanism for rotating a payload in two DOFs disclosedherein, at zero position.

FIG. 2B shows in side view the mechanism of FIG. 2A at a rotatedposition, around both rotation axes;

FIG. 3A shows schematically in a perspective view yet another embodimentof a rotation mechanism for rotating a payload in two DOFs disclosedherein, at zero position.

FIG. 3B shows the mechanism of FIG. 2A in a top view;

FIG. 3C shows one perspective view of an exemplary case in which thefirst rotation arm is rotated around the first DOF;

FIG. 3D shows another perspective view of the exemplary case of FIG. 3C.

DETAILED DESCRIPTION

FIG. 1A shows schematically in a perspective view an embodiment of arotation mechanism (or simply “mechanism”) disclosed herein and numbered100. Mechanism 100 is used for rotating a payload 102 in two DOFsdisclosed herein, at zero position (initial position, without anyactuation, not rotated). An exemplary XYZ coordinate system shownapplies also to all following perspective views. Payload 102 is shown asa prism, but may be any element, and in particular any optical element,such as (and not limited to) a lens, an image sensor, a prism, a mirroror an entire camera. Mechanism 100 includes a static base 104 (i.e. afixed base that does not move), a first rotation arm 106, a secondrotation arm 108 and a magnetic follower 116. First rotation arm 106 canrotate relative to static base 104 around a first rotation axis 109(shown exemplarily in the Y direction). First rotation axis 109 passesthrough a first rotation joint 110 that couples first rotation arm 106mechanically with static base 104 (e.g. using a ball bearing). Secondrotation arm 108 has a shape of a circle section with a center on afirst rotation axis 109. A second rotation axis 118 passes through asecond rotation point 112 that mechanically connects second rotation arm108 with static base 104 (e.g. using a ring ball bearing). Secondrotation arm 108 can rotate relative to static base 104 around secondrotation axis 118 (shown exemplarily in the X direction). The first andsecond rotation axes may be perpendicular to each other. Magneticfollower 116 may made of a permanent (fixed) magnet (or at least the tipfacing second rotation arm is made of a permanent magnet). Secondrotation arm 108 may be made of a ferromagnetic material. Alternatively,the second rotation arm may be made of a rigid material such as aplastic material or a non-ferromagnetic metal covered with aferromagnetic material on a side facing magnetic follower 116. Magneticfollower 116 is distanced from second rotation arm 108 by an air-gap 111(FIG. 1C), and allows payload 102 to follow second rotation arm 108without having magnetic follower 116 touch second rotation arm 108directly.

First rotation arm 106 and second rotation arm 108 can be rotatedrelative to rotation joints 110 and 112 respectively (each arm aroundone rotation point). The rotation can be performed by any motor (e.g.stepper, DC, brushless, VCM, etc.). An inner rotation point 114 connectspayload 102 to first rotation arm 106 (e.g. using ring ball bearing) andallows payload 102 to rotate in a second DOF (see FIG. 1E). Firstrotation arm 106, first rotation joint 110 and inner rotation point 114are similar to elements of a gimbal. Note that inner rotation point 114is on second rotation axis 118 at zero point (as seen in FIG. 1A) butwhen first rotation arm 106 is rotated inner rotation point 114 rotateswith it and is shifted from second rotation axis 118, as seen forexample in FIG. 2B.

FIG. 1B shows mechanism 100 coupled with exemplary first and secondmotors 120 and 122, which drive a rotation movement around the first andsecond rotation axes respectively. Advantageously, motors 120 and 122are stationary relative to static base 104. In other embodiments, motors120 and 124 may have different shapes and sizes, may be equal to oneanother or different in size, technology of actuation, etc.

FIG. 1C shows mechanism 100 in a zero, non-rotated position (same as inFIG. 1A), while FIG. 1D shows mechanism 100 in a second, rotatedposition. Both FIGS. 1C and 1D are given in a side view in an exemplaryX-Z plane (looking from positive to negative Y direction). In FIG. 1D,first rotation arm 106 is rotated around first rotation axis 109 (e.g.using first motor 120) relative to the base 104 and payload 102 rotateswith it. Magnetic follower 116 stays distanced from second rotation arm108 by a constant distance (air-gap 111). The rotation around firstrotation point may be in any angle α. The angle limitation shown inFIGS. 1A-E is due only to the length of second rotation arm 108, whichas shown is about a quarter of a circle in length. In other embodiments,the second rotation arm may be a complete circle, such that rotation ofthe first rotation arm around the first rotation axis may be up to 360degrees.

FIG. 1E shows the rotation of second rotation arm 108 (e.g. using secondmotor 122) around the second rotation axis. Magnetic follower 116 ispulled to second rotation arm 108 by the magnetic force and thus rotateswith it and rotates payload 102 relative to first rotation arm 106around inner rotation point 114 in the second DOF. The rotation of themagnetic follower is independent of the rotation of first rotation arm106 around first rotation axis 109 in the first DOF, because magneticfollower 116 is pulled to the second rotation arm 108 equally in allpositions along first DOF. Magnetic follower 116 following secondrotation arm 108 forms a “sliding joint”, e.g. a joint that allowsmagnetic follower 116 to follow second rotation arm 108 in one (first)DOF while sliding without interference in a second DOF.

FIGS. 2A and 2B show in perspective views another embodiment of arotation mechanism disclosed herein and numbered 200. Mechanism 200 issimilar to mechanism 100, with identical parts in both mechanismsnumbered with identical numerals. In mechanism 200, the payload is aexemplarily a camera 202, and a second rotation arm 208 is a fullcircle, which enables rotation around the first rotation axis by 360degrees. In FIG. 1A, mechanism 200 is shown in a rest (non-rotated)position, while in FIG. 1B, mechanism 200 is shown in position rotatedby 30 degrees from the rest position.

FIGS. 3A-D show yet another embodiment of a rotation mechanism disclosedherein and numbered 300. Rotation mechanism 300 is similar to mechanism100, with identical parts in both mechanisms numbered with identicalnumerals. Relative to mechanism 100, mechanism 300 is equipped with twoposition sensing mechanisms, enabling determining a relative position(orientation/rotation) of payload 102 relative to frame 104 in two DOF.The position sensing mechanisms comprise at least one pair of a magnetand a Hall sensor. In some embodiments, a position sensing mechanism maycomprise more than one magnet and/or more than one Hall sensor. FIG. 3Ashows a perspective view of mechanism 300, and FIG. 3B shows a top view.Mechanism 300 comprises a first magnet 302 rigidly coupled to firstrotation arm 106 and a first Hall sensor 304 rigidly coupled to base104. Mechanism 300 further comprises a second magnet 306 rigidly coupledto payload 102, and a second Hall sensor 308 rigidly coupled to base104. In an example, the position of the second Hall sensor is on firstrotation axis 109. In an example, Hall sensors 304 and 308 can measurethe intensity of the magnetic field in the Y direction. In particular,first Hall sensor 304 is positioned close to first magnet 302 and canmeasure the intensity of the magnetic field of first magnet 302, whichcan be correlated with the rotation of the payload around the first DOF.Second Hall sensor 308 is positioned close to second magnet 306 and canmeasure the intensity of the magnetic field of second magnet 306, whichcan be correlated with the rotation of the payload around the secondDOF. FIGS. 3C and 3D show, from two different perspective views, anexemplary case where the first rotation arm 106 is rotated around thefirst DOF (e.g. in 30 degrees). The relative position of first magnet302 and first Hall bar 304 is changed, while the relative position ofsecond magnet 306 and second Hall bar 308 is unchanged. Similarly, whenrotating payload 102 around the second DOF using second rotation arm108, the relative position of first magnet 302 and first Hall bar 304 isunchanged, while the relative position of second magnet 306 and secondHall bar 308 is changed. Thus the measurements of the two DOFs aredecoupled from each other.

In summary, disclosed above are rotation mechanisms having a design withat least the following advantages:

-   -   Ability to rotate around two degrees of freedom.    -   The motors are stationary.    -   Only three mechanical connection points (bearings) are used to        create the rotation, compared with at least four bearings in        other designs in which the motors are stationary, for example in        “Dynamic modeling and base inertial parameters determination of        a 2-DOF spherical parallel mechanism” Danaei, B. et al.,        Multibody Syst. Dyn. (2017) 41: 367,        doi:10.1007/s11044-017-9578-3, and “Optimal Design of Spherical        5R Parallel Manipulators Considering the Motion/Force        Transmissibility”, Chao Wu et al., J. Mech. Des. (2010) 132(3),        doi: 10.1115/1.4001129.

While this disclosure describes a limited number of embodiments, it willbe appreciated that many variations, modifications and otherapplications of such embodiments may be made. For example, the magneticfollower can be replaced with a mechanical follower.

In general, the disclosure is to be understood as not limited by thespecific embodiments described herein, but only by the scope of theappended claims.

All references mentioned in this specification are herein incorporatedin their entirety by reference into the specification, to the sameextent as if each individual reference was specifically and individuallyindicated to be incorporated herein by reference. In addition, citationor identification of any reference in this application shall not beconstrued as an admission that such reference is available as prior artto the present application.

1. A rotation mechanism for rotating a payload in two, first and seconddegrees of freedom (DOF), comprising: a) a static base; b) a firstrotation arm coupled mechanically to the static base through a firstrotation joint and used for rotating the payload relative to the staticbase around a first rotation axis that passes through the first rotationjoint; c) a second rotation arm coupled mechanically to the static basethrough a second rotation joint and used for rotating the payloadrelative to the static base around a second rotation axis that passesthrough the second rotation joint; and d) a follower member rigidlycoupled to the payload and arranged to keep a constant distance from thesecond rotation arm, wherein the rotation of the first arm rotates thepayload around the first DOF and wherein the rotation of the second armrotates the payload around the second DOF.
 2. The rotation mechanism ofclaim 1, wherein the payload is coupled mechanically to the firstrotation arm through an inner rotation joint.
 3. The rotation mechanismof claim 1, further comprising a first motor for rotating the payloadrelative to the static base around the first rotation axis and a secondmotor for rotating the payload relative to the static base around thesecond rotation axis, wherein the first and second motors are rigidlyattached to the static base.
 4. The rotation mechanism of claim 1,wherein the follower member is a magnetic member separated from thesecond rotation arm by a constant air-gap.
 5. The rotation mechanism ofclaim 2, further comprising a first motor for rotating the payloadrelative to the static base around the first rotation axis and a secondmotor for rotating the payload relative to the static base around thesecond rotation axis, wherein the first and second motors are rigidlyattached to the static base.
 6. The rotation mechanism of claim 2,wherein the follower member is a magnetic member separated from thesecond rotation arm by a constant air-gap.
 7. The rotation mechanism ofclaim 3, wherein the follower member is a magnetic member separated fromthe second rotation arm by a constant air-gap.
 8. The rotation mechanismof claim 1, wherein the second rotation arm includes a ring sectioncentered around the first rotation axis.
 9. The rotation mechanism ofclaim 1, further comprising at least one sensing mechanism fordetermining a position of the payload.
 10. The rotation mechanism ofclaim 9, wherein the at least one sensing mechanism comprises at leastone pair of a magnet and a Hall sensor.
 11. The rotation mechanism ofclaim 9, wherein the at least one sensing mechanism is operable todetermine a position of the payload relative to the static base in thefirst and second DOFs.
 12. The rotation mechanism of claim 10, whereinthe at least one pair of a magnet and a Hall sensor comprises a firstpair of a magnet and a Hall sensor that allows determinination of arotation of the payload around the first DOF, and a second pair of amagnet and a Hall sensor that allows determinination of a rotation ofthe payload around the second DOF.
 13. The rotation mechanism of claim11, wherein the determinations of the position of the payload relativeto the static base in the two DOFs are decoupled from each other.